An active transmission/reception module can be used, for example, in a monolithically integrated microwave circuit embodiment (MMIC) for a radiator element operating in both vertical and horizontal polarization in an electronically phase-controlled antenna. Such an active transmission/reception module is discussed, for example, in M. Priolo et al, "Multifunction Transmit and Receive Modules for EW Arrays", Microwave Journal, pp. 83-92 (February 1991). The active transmission/reception module functions as an electronic counter-measure for active jamming in the transmit mode, and as an electronic reconnaissance system for frequency and signal identification in the receive mode. The active transmission/reception module is capable of vertical and horizontal polarization in both the transmit and receive modes.
Such an active transmission/reception module provides a 90.degree. phase difference between the two power terminals, achieved by using quadrature hybrids and a polarization switch, in order to combine all of the transmission energy either at the vertical or horizontal polarization terminals during polarization switching. In the receive mode, the reception amplifiers are connected to the reception path according to the polarization selected, such that a deterioration of the noise factor is avoided. A transmission amplifier/four-way power-combining network includes a number of shunt switches. Transmit/receive switching is achieved by the shunt switches. For example, in the transmit mode, the switches operate in a condition having low loss, whereas the switches are switched into a highly reflective condition in the receive mode, thereby effecting conduction of the signal into the reception channel. However, such an active transmission/reception module requires the use of relatively complicated transmission/reception switches, as well as three dB hybrids.
Other known active transmission/reception modules in an integrated microwave circuit embodiment for use in an electronic phase-controlled antenna are discussed, for example, in M. E. Davis et al., "L-Band T/R Module for Airborne Phased Array", Microwave Journal, pp. 54-60 (February 1977), and in P. Bradsell, "Phase Arrays in Radar", Electronics & Communication Engineering Journal, pp. 45-50 (April 1990). Such transmission/reception modules, however, are only operative with respect to a single polarization, such that polarization switching is not required. A power amplifier is provided, and disposed in the transmission path between the transmit contact of the transmission/reception switch and a circulator terminal. Further, a low-noise amplifier is provided, and disposed in the reception path between another circulator terminal and the receive contact of the transmission/reception switch.
Based on the known transmission/reception modules, if one were to design a module for supplying both a radiator element for horizontal polarization and a radiator element for vertical polarization, then one would be led to connect a polarization change-over to the circulator and to apply its change-over contacts directly to the radiator element terminals for the respective polarizations. However, the entire antenna system including the transmission/reception module would deteriorate by at least 2 dB due to the loss contribution of such an arrangement of the polarization change-over.
Comparing such an embodiment of a transmission/reception module to a transmission/reception module without power polarization switch-over, the transmission output power would be lower by at least 1 dB and the reception noise factor would be higher by at least 1 dB. On the other hand, if the polarization switch-over were avoided, the relationship between the reception signal and the noise of the antenna system would be improved by approximately 2 dB with the same output power of the terminating receiver. As 2 dB approximately corresponds to a factor of 1.6, a 2 Watt power amplifier in a transmission/reception module without power polarization switch-over results in the same relationship between the reception signal and noise of the antenna system as in a 3.2 Watt power receiver in a transmission/reception module having power polarization switch-over. Thus, assuming a 40% power-enhanced power amplifier and without considering the power loss in the antenna power distribution system, approximately 38% of the power supply, or approximately 3 Watts per transmission/reception module, can be saved during the transmission phase in the antenna system when no polarization switch-over occurs between the power amplifier and the radiator element.